I'm going to have to upset Peter and agree with NeilC.
If you read my post [(https://support.stagetraxx.com/d/914-retaining-a-song-in-a-playlist-after-updating-it/1)] I too have had the problem of files failing to import or importing with a time of 0, etc. It's not because you normalized the songs. I had these errors with MP3 files all the time so I tried going with M4A files but it started doing the same albeit less frequently.
@NeilC this happens when you import all the iTunes files in one go. I think you should avoid using iTunes as a go-between step. The problem with iTunes is the number of times you have to store a track. You need your source files on PC, then you have to load them into iTunes, then hope they sync correctly. Then you have to import them from iTunes into Stage Traxx.
There are other (maybe seemingly more difficult) ways to get the files into the iPad without iTunes or USB. The problem is, and I'll create a video to show it, even if you import over a network connection which is how I do it, or from iCloud, you will get the same problem if you are importing that many files in one go.
That's the problem. I believe from a programmatic point of view that it is an overload of the import process.
I didn't pursue this in my post because it was me against the world.
But there are ways that work around this, and that's what you have to do to put bread on the table.
I'd say the best way to get a large number of songs in without error is to copy them directly into the Stage Traxx 3 folder via Files app on your iPad.
Don't use ST3's import. That's where I believe the problem is. But, if you really want to do it that way, import songs in batches of 30.
Probably the easiest way to get them directly into the ST3 folder, as PC user, is to use OneDrive or DropBox. (I use an SMB network connection over WiFi, but that's not for everyone.) Put all your songs on the cloud. Then, link up access to whatever cloud you use in iPad's Files app. Then in files app, copy over all the songs into the Stage Traxx 3 folder, ie. "On My iPad". After that, go into ST3 and pull down the song list which will trigger a refresh and effectively import your songs..